A complementation analysis of transfer-deficient mutants of RP1 will be carried out. To aid this, Co1E1 derivatives carrying RP1 tra but not inc genes have been obtained. Deletion mutants obtained from RP1 derivatives carrying a temperature-sensitive prophage will be used to map the tra genes. Also, a series of RP1 delection mutants able to replicate in a P.aeruginosa (B3) lysogen are being examined both genetically and by molecular techniques to determine the extents of the deletions and the locations of RP1 genes. The protein products of some RP1 tra and other genes will be identified in a minicell system.